The Organization for the Prohibition of Chemical Weapons (OPCW) said Wednesday that Syria was expected to present a detailed plan for the destruction of its chemical arsenal in the next 24 hours, dpa reported.
"We expect Syria's initial declaration of its chemical weapons programme within the next 24 hours," the watchdog's spokesman Michael Luhan told reporters at The Hague-based OPCW.
"We're reaching the end of this first stage, during which we needed to verify the chemical warfare programme by visiting all the disclosed sites."
Luhan added the OPCW and UN teams had already visited 18 of 23 disclosed sites. Experts have destroyed production equipment at almost all of them, he said.
"We are confident that we are going to achieve that inside of the deadline of 1st November," he said, referring to a deadline for destroying Syria's chemical production facilities. "Destruction activities have now been conducted at all but one of the relevant sites in Syria."
The UN Security Council in September passed a resolution backed by a US-Russian deal to eliminate Syria's chemical stockpile by mid-2014.
On the ground in Syria Wednesday, rebel groups - including the al-Qaeda-linked Islamic State of Iraq and the Levant - seized government troop outposts in the central province of Homs, reported a pro-opposition group.
The Britain-based Syrian Observatory for Human Rights said the outposts are in the village of Mahin where large arms depots are located.
The Observatory added that Islamist opposition rebels also seized a gas well located near the Christian town of Sadad in Homs, prompting an exodus by local residents.
At least five civilians were, meanwhile, killed and 20 wounded when mortar shells landed in the capital Damascus, according to the Observatory.
In Brussels, EU President Herman Van Rompuy warned that Syria's 31-month conflict puts the region's stability at stake.
"The terrible conflict in Syria threatens the stability of neighbouring countries. An end must be put to violence and to suffering," he said.
"The EU is urging all sides of the conflict to respond positively to the call of the UN secretary general for a peace conference in Geneva before the end of November," he added, referring to peace talks proposed by Russia, Damascus' ally, and the United States.
More than 100,000 people have been killed in Syria's conflict that started with peaceful pro-democracy protests in March 2011, according to the United Nations.